At some point, TradingView changed something about how it parses the strings I was using for charts like this. As this one no longer works, here's a few more strings for charts I'm watching that convey the same or very similar data:
Same(using the actual indices/real-time data): (BITSTAMP:BTCUSD+BINANCE:BTCUSDT+COINBASE:BTCUSD+BITFINEX:BTCUSD+KRAKEN:XBTUSD)/5-TVC:NDX-TVC:DJI-SP:SPX
Similar(conveys a ratio instead of a spread, also using the actual indices): (TVC:DJI+TVC:NDX+SP:SPX)/BITSTAMP:BTCUSD
Sameish(using futures instead): (BITSTAMP:BTCUSD+BINANCE:BTCUSDT+COINBASE:BTCUSD+BITFINEX:BTCUSD+KRAKEN:XBTUSD)/5-NQ1!-ES1!-DJIA1!
Similar(same as the first "similar" one, but using futures instead): (NQ1!+ES1!+DJIA1!)/BITSTAMP:BTCUSD
It just so happens that the sum of the indices at the moment is exactly 10 times that of the price of bitcoin, which is where it was in September of 2017 right before the crazy bitcoin FOMO.